Radial piston pump and motors comprise a pintle valve having a rotor rotatably mounted thereon and a plurality of pistons secured to the rotor and disposed circumferentially thereabout. A closed cylinder is reciprocally mounted on the end of each of the piston means for communicating pressurized fluid to an outlet of the pump upon rotation of the rotor which is eccentrically mounted relative to an internal chamber defined by internal wall portions having the cylinders maintained in sliding bearing contact therewith. Any such pumps must exhibit a sufficiently high degree of structural integrity to enable them to operate at high speeds as high as 10-12 m. rpm. In addition, it is further desirable that the pump or motor be constructed and arranged to facilitate economical manufacture and expeditious assembly and disassembly for servicing purposes.